Aryl 2-thienyl sulfides and aryl 2-thienyl sulfones

A method was developed for the synthesis of the previously unknown aryl 2-thienyl sulfides; the method is based on the reaction of 2-chlorothiophene and its derivatives with thiophenols in the gas phase at 450–500°C. The synthesized sulfides were oxidized to the corresponding aryl 2-thienyl sulfones, which were also previously unknown. 2,5-Dichlorothiophene reacts with excess thiophenol to give 2,5-bis(phenylthio)thiophene, which is oxidized to the corresponding disulfone.     

Steric structure of some tert-butyl aryl sulfones

Conclusions Aryl is in a skewed position (=73±13) in tert-butyl aryl sulfones. There are no significant changes in the conformation of the sulfone molecules when methyl is replaced by the tert-butyl radical.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2057–2060, September, 1981.The authors thank A. N. Vereshchagin for valuable consultations and for his interest in the paper.     

Theoretical studies of electronic and crystal structure properties of anhydrous mercury oxalate

The results of theoretical analysis of the crystal structure and bonding in relation to thermal decomposition process in anhydrous mercury oxalate are presented. The methods used Bader’s Quantum Theory of Atoms in Molecules formalism with bond order model (by Cioslowski and Mixon), applied to electron density obtained from ab initio calculations carried out with FP-LAPW Wien2k package (Full Potential Linearized Augmented Plane Wave Method) and Brown’s Bond Valence Model are described. The analysis of the obtained results shows that most probably the thermal decomposition process of mercury oxalate should lead to metal and CO₂ as products (as it is experimentally observed). Presented results (as well as the results of our similar calculations carried out previously for zinc, cadmium silver, cobalt and calcium oxalates) allow us to state that such methods (topological and structural), used simultaneously in analysis of the crystal structure and bonding properties, provide us with the additional insight into given compound’s behavior during thermal decomposition process. As a result, these methods can be considered as valuable supporting tool in the analysis of thermal decomposition process in given compound.     

硫化反式聚异戊二烯电子性质的理论化学研究

应用量子化学计算方法,对反式聚异戊二烯本征态和硫化态结构的能量及电子性质等进行了计算.结果表明,当聚异戊二烯掺杂硫后,相邻两链之间的距离a⊥变窄,体系的总能量降低,从而使整个掺杂体系更加稳定.另外,在硫化聚异戊二烯分子中,S原子位于两个相邻聚异戊二烯链之间,并偏向于其中一个分子链的C C双键的一侧,即与相邻两链中相对应的两个C C双键形成π-p-π共轭体系,增加了电子在两个聚异戊二烯链间的流动性,从而使硫化的反式聚异戊二烯更加稳定.另外,根据固体能带理论,采用量子化学EHMO方法,对反式聚异戊二烯本征态和硫掺杂态的能带结构进行了计算,根据硫化前后能隙和带宽的变化,解释了反式聚异戊二烯掺杂后呈现电导率各向异性的原因.     

Theoretical studies of electronic structure and structural properties of anhydrous alkali metal oxalates

Nanocrystalline LiMn₂O₄ was synthesized by calcining LiMn₂(CO₃)_2.5·0.8H₂O above 600 °C in air. The precursor and its calcined products were characterized by thermogravimetry and differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. The result showed that highly crystallization LiMn₂O₄ with cubic structure [space group Fd-3m(227)] was obtained when the precursor was calcined at 600 °C in air for 1.5 h. The thermal process of the precursor in air experienced three steps which involved, at first, the dehydration of 0.8 water molecules, then decomposition of MnCO₃ into Mn₂O₃, at last, reaction of Mn₂O₃ and Li₂CO₃ into cubic LiMn₂O₄. Based on Starink equation, the values of the activation energies associated with the thermal process of LiMn₂(CO₃)_2.5·0.8H₂O were determined. Besides, most probable mechanism functions and thermodynamic functions (ΔS ^≠, ΔH ^≠, and ΔG ^≠) of thermal processes of LiMn₂(CO₃)_2.5·0.8H₂O were also determined.     

Theoretical studies of electronic structure and structural properties of anhydrous alkali metal oxalates

The theoretical analysis of electronic structure and bonding properties of anhydrous alkali metal oxalates, based on the results of DFT FP-LAPW calculations, Bader’s QTAIM topological properties of electron density, Cioslowski and Mixon’s topological bond orders [reported in the first part of this paper by Kole?yński (doi:10.1007/s10973-013-3126-z)] and Brown’s Bond Valence Model calculations, carried out in the light of thermal decomposition pathway characteristic for these compounds are presented. The obtained results shed some additional light on the origins of the complex pathway observed during thermal decomposition process (two stage process, first the formation of respective carbonate and then decomposition to metal oxide and carbon dioxide). For all structures analyzed, strong similarities in electronic structure and bonding properties were found (ionic-covalent bonds in oxalate anion with C–C bond as the weakest one in entire structure and almost purely ionic between oxalate group and alkali metal cations), allowing us to propose the most probable pathway consisting of consecutive steps, leading to carbonate anion formation with simultaneous cationic sublattice relaxations, which results in relative ease of respective metal carbonate formation.     

芳汞基芳基硫化合物的合成与波谱性质研究

芳汞基氯化汞和苯硫酚或对甲基硫酚在乙醇中反应合成了两个系列共32种芳汞基芳基硫化合物,其中22种为新化合物。 研究了这些化合物的紫外吸光谱和核磁共针氢谱,所得结果表明,对此两个系列的标题化合物,在△γ~MAX~与Hammett取代基常数 ~P之间有良好的线性关系,但共轭作用未完全通过硫原子贯穿到整个分子。也对取代基~1H NMR的影响进行了研究。     

Theoretical studies on electronic structure and magnetic properties of mixed‐valence uteroferrin active site

The electronic structure and magnetic interaction of the active site of pig purple acid phosphatase (PAP, uteroferrin) were investigated using pure DFT (UBLYP) and hybrid DFT methods (UB3LYP and UB2LYP). Uteroferrin catalyzes the hydrolysis of a phosphate ester under acidic conditions and contains a binuclear iron center. The mammalian PAPs are expected to be targets for drug design of osteoporosis. Their active sites are typical examples of the Fe(II)‐Fe(III) mixed‐valence system. We studied double exchange interaction of the mixed‐valence system, using the potential energy difference between the Fe(II)‐Fe(III) and the Fe(III)‐Fe(II) states. The pathway of the antiferromagnetic coupling between Fe(III) and Fe(II) were also discussed by using chemical indices, which are evaluated by the occupation numbers of singly occupied natural orbitals. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Theoretical studies on the structure and spectroscopic properties of pseudohalides

Pseudohalogen-containing compounds have attracted significant interest among nonmetal chemists and theorists, not only owing to their potential use in various fields but also due to difficulties in their experimental preparation and characterization. Since its introduction in 1925, the pseudohalide principle has been used extensively and, therefore, a remarkable progress has been made in the experimental and theoretical research on the compounds of this kind. In this work, we review studies on structural investigations and theoretical characterizations of several pseudohalide-containing compounds in order to contribute to better understanding of the chemistry of many such species.     

新型低带隙聚合物结构和性质的理论研究

本文将3,4-次乙烯二氧噻吩（VDOT）与噻吩并[3,4-b]吡嗪（TP）,呋喃并[3,4-b]吡嗪（FP）和6H-吡咯并[3,4-b]吡嗪（PP）组合,获得了一系列3,4-次乙烯二氧噻吩衍生物.采用密度泛函理论（DFT）在B3LYP/6-31G＊理论水平下对其单体、低聚物和聚合物的结构和电子性质进行了深入的理论研究.通过分析键长的变化、中心键性质,Wiberg键级（WBI）以及核独立化学位移,发现随着聚合度的增加物质的共轭性也随之增加.为了了解不同的VDOT与TP、FP、PP比例对电子性质的影响,对V-P比例为1：1、1：2和2：1时的计算结果进行了对比分析,结果表明,V-P比例为1：2化合物共轭性最好,而2：1的共轭性最差.由于1：2的二聚物具有较大的电子迁移速率,其相应的聚合物可能是潜在的电子传输材料.同时,聚合物的能带结构显示V-P比例为1：1的聚合物（包括（VDOT-TP）n,（VDOT-FP）n和（VDOT-TP）n）具有相对低的带隙和很宽的带宽,可以做为潜在的导电材料.另外,（VDOT-BTP）n和（VDOT-BFP）n有着非常低的带隙（分别为0.73和0.87eV）,且拥有合适的带宽,也是良好的本征导电材料.     

洛汾碱衍生物的电子结构及光谱性质的理论研究

采用密度泛函理论(DFT)的B3LYP/6-31G*方法,对4种洛汾碱类化合物的几何构型进行了优化,在此基础上计算分子的电子结构,并结合有限场FF方法研究了二阶非线性光学(NLO)性质.用含时密度泛函理论(TD-DFT)对上述化合物分子进行吸收光谱的研究.研究表明在4,5-二-苯基-2-对甲酰苯基咪唑生色团中4,5苯环上引入硝基和3位N原子引入苄基改变分子的共轭平面,使二阶非线性极化率总有效值(βtot)减小,吸收峰总体蓝移.同时还发现,在CH2Cl2溶剂中a和c分子的λmax主要来源于HOMO→LUMO的π一π*跃迁,b和d分子的λmax主要来源于HOMO→LUMO+2的π→π*跃迁.     

Theoretical studies on the electronic structure of Ti8C12 isomers

Density functional calculation are performed to study Ti(8)C(12) isomers (T(d), C(3v), and D(2d)) in the neutral, cationic, and anionic charge states. C(3v) symmetry is found to be the most stable geometry for the neutral and anion, and the C(3v) and D(2d) isomers to be quasi-iso-energetic lowest for the cation. The electronic structure analysis show that d electron tends to be localized in the ground state. The theoretical assignment for the features in the experimental photoelectron spectra is given. All results obtained are in good agreement with the available experimental data and indicate that the C(3v) and D(2d) isomers may coexist in the photoelectron spectroscopy experiment.     

Theoretical studies of structural and electronic properties of AlnAsn clusters

We present theoretical results of size dependent structural, electronic, and optical properties of ligand‐free stoichiometric Al_nAs_n clusters of zinc‐blende modification. The investigation is done using a simplified parametrized linear combination of atomic orbital–density functional theory‐local density approximation–tight‐binding (LCAO–DFT–LDA–TB) method and consider clusters with n up to around 100. Initial structures have assumed as spherical parts of infinite zinc‐blende structure and then allowed to relax to the closest local‐energy‐minimum structure. We analyze the radial distributions of atoms, Mulliken populations, electronic energy levels (in particular, HOMO and LUMO), bandgap, and stability as a function of size and composition. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Theoretical calculation of the structure and electronic properties of dihydrothymines and dihydrouracils

A number of Wolfsberg-Helmholz (W-H) type calculations for VO(H₂O) ₅ ⁺⁺ are reported. The aim of the work is twofold: to test the viability of single Slater type mimics of SCF orbitals, and to remove a number of the more drastic assumptions in the original Ballhausen-Gray (B-G) calculations. It is shown that single Slater type orbitals may be obtained in such a way as to more or less reproduce results of W-H calculations using SCF-functions. It is shown that removal of B-G approximations does not change the relative one-electron MO ordering of the B-G scheme; however, the energy gaps between the levels are changed considerably. The effects of displacing the vanadyl group from the equatorial plane are shown to be important.

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Zusammenfassung Eine Anzahl von Wolfsberg-Helmholz (W-H) Rechnungen für VO(H₂O) ₅ ⁺⁺ sind durchgeführt worden, um einerseits SCF-adjustierte einfache Slaterfunktionen zu testen und andererseits eine Anzahl von Vereinfachungen der ursprünglichen Rechnungen von Ballhausen u. Gray (B-G) zu eliminieren. Es zeigt sich, daß es einfache Slaterfunktionen gibt, die bei Rechnungen nach W-H ähnliche Ergebnisse wie SCF-Funktionen liefern, und daß Rechnungen mit und ohne den Näherungen von B-G die gleiche Reihenfolge der MOs, aber verschiedene Einteilchenenergien liefern. Die Verschiebung der Vanadylgruppe aus der horizontalen Ebene heraus beeinflußt die Elektronenstruktur stark.

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Résumé Un nombre de calculs d'après Wolfsberg-Helmholz (W-H) est exécuté sur VO(H₂O) ₅ ⁺⁺ pour tester des fonctions simples de Slater représentantes des orbitales SCF, et pour éliminer un certain nombre d'hypothèses du calcul original de Ballhausen-Gray (B-G). Il est démontré que des simples STO sont obtenables qui produisent environ les resultats d'un calcul W-H à l'aide des fonctions SCF, et que les calculs soit avec soit sans approximation B-G donnent le même ordre de MO mais une énergie différente. L'effet de délocalisation de la group Vanadyl du plan horizontal est montré d'être très important pour la structure électronique.

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This work was supported by research grants from the United States Atomic Energy Commission — Biology Branch and The National Science Foundation.     

荧光素及其衍生物电子结构与光谱性质的理论研究

用ZINDO、从头算和密度泛函理论方法研究荧光素及其衍生物的电子结构和光谱性质.计算结果表明母体双阴离子荧光素分子(1)与单(2)、双(3)取代形成的单阴离子荧光素分子的基态电子结构不同,而且1与2和3的基态和激发态的电子转移方向相反.体系1~3的最大吸收波长依次发生红移,与实验结果相符合.     

Methyl and trifluoromethyl vinyl sulfones: Steric and electronic structure

The potential functions of internal rotation around the $C_{sp^2 } $ -S bond in the compounds H₂C= CHSO₂CY₃ (Y = H or F) were obtained; the stationary points were revealed and identified by solving vibrational problems [MP2(full)/6-31+G(d), B3PW91/6-31+G(d), B3PW91/6-311+G(3df,p)]. The energetically favorable conformations were determined, and the internal rotation barriers and geometric parameters of the molecules were estimated. The wave functions [MP2(full)/6-31+G(d)] were analyzed by the NBO method. The energies, populations, and dipole moments of natural orbitals of bonds and lone electron pairs, the main types of donor-acceptor interactions, the bond orders (Wiberg indices), and the natural charges on atoms were estimated. The steric and electronic structures of vinyl sulfoxides and sulfones are compared.     

New insights into the titanium-mediated enantioselective oxidation of fluorinated aryl benzyl sulfides and aryl phenacyl sulfides

A fruitful switch from tert-butyl to cumene hydroperoxide was able to overcome a difficulty arose in the enantioselective oxidation of fluorinated aryl benzyl sulfide with hydroperoxides in the presence of a titanium/(S, S)-hydrobenzoin catalyst. New experiments show the complementarity of the old and the new protocols and indicate unequivocally the right choice leading to the corresponding highly enantioenriched sulfoxides. Moreover, in a totally unexpected way, the new protocol was able to overcome another difficulty arose in another field of research, that is the enantioselective oxidation of a fluorinated aryl phenacyl sulfide. Also in this case, the complementarity of behavior is acting. Finally, this investigation gives new support to the attribution of configuration of sulfoxides with ECD techniques, but only if the protocol outlined in our past research was followed thoroughly.